Application of synchrotron X-ray fluorescent analysis to studies of the records of paleoclimates of Eurasia stored in the sediments of Lake Baikal and Lake Teletskoye

Multi-element SRXRF of sediments of Lake Baikal (East Siberia) with samples taken at 10 cm intervals from a core spanning the last 250 ky revealed nin e peaks of "warm" signals like Sr/Ba(Rb,Cs) and U/Th corresponding to Ocean ic Isotope Stages 1,3,5a,5c,5e,7 and 9, and six peaks of "cold correlator" corresponding to OIS 2,4,5d,6 and 8. A slab (1500-2200mm below the sediment surface) taken from another core was studied by scanning SRXRF. This inter val corresponds to the Siberian Karga interstadial (OIS3, 24-58 ky BP). It hosted two peaks of diatom algae frustulles, indicators of warmer climates. The scanning was performed at a temporal resolution of ca. 50yr. Ratios of concentrations like Sr/Rb(Ba,Cs,Ti,Fe) (Nucl. Instr. and Meth. A 448(1-2) (2000) 384. Nucl, Instr. and Meth. A 448 (1-2) (2000) 400) appeared to be m ore sensitive proxies of warm climates, compared to total diatoms, and reve aled at least six pronounced cycles of abrupt warming and cooling episodes. each lasting a few millennia. These fluctuations may reflect a response of the catchment basin of the Lake Baikal to abrupt global climate cycles rec orded in the ice of Greenland and in the sediments of North Atlantic (Natur e 364 (1993) 142: Science 278 (1997) 1257, Science 288 (2000) 128). SRXRF a pplied to the sediments of Lake Teletskoye (West Siberia, Altai Mountains) of the last 600 yr provided a temporal resolution of 1.2-1.8yr. The profile s of a few elements like K, Ca. Ti, Fe, V revealed oscillations with a peri odicity of 9.4yr over the time interval between years 1400 and 1600. Oscill ations faded out after the cooling of 1600-1700 (The Maunder interval). Per iodic oscillations between years 1400 and 1600 seem to correspond to period ic changes in the height of oceanic tides (9yr (PNAS 94 (1997) 8321, PNAS 9 7 (2000) 3814)) rather than to the solar activity cycles (periodicity of 11 yr). (C) 2001 Elsevier Science B.V. All rights reserved.